Apparatus for conveying pulverized material



Aug. 15, 1944. A. BAKER 2,355,774

' APPARATUS FOR commune runvan'rznn 'uusnm.

Filed Nov. 29, 1941 2 Sheets-Sheet 1 INVENTOR. ALBERT L. BAKER Aug. 15,1944. E A. I... BAKER 2,355,774

' Arm'rus FOR ponvsrme YULVERIZEDVIIATER'IAL Filed gm. 29,1941 2 Sheets-Shoot 2 INVENTOR..

ALBERT 4.54m?

" *llm ra AUDRIWYS Patented Aug. .15, 1944 UNITED STATES APPARATUS FORCONVEYING PULVERIZED MATERIAL Albert L. Baker, Summit, N.-J., assignor,by meme assignments, to Fuller Company, Oatasauqua, Pa., a corporationof Delaware Application November 29, 1941, Serial No. 420,991

7 Claims.

minuted material through, a casingby means of a rapidly rotating screwwhich compacts the material as it advances. Adjacent the delivery end ofthe screw, compressed gas is injected into the stream to aerate thematerial. In some of the devices the compacting action of the screwresults in the formation of a plug, or area of increased density, whichforms a seal against preaeration of the pulverized material in the con.-

veyor screw due to blow-back of the gas'into the conveyor casing.

It has been found that the apparatus and methods above referred to donot operate equally well with all materials and under all conditions.Particularly lacking in many of the present devices has been asatisfactorily uniform discharge at the delivery end of the screwconveyor immediately preceding the point of aeration. A principal objectof my invention. therefore, is to provide improved conveying apparatusof the character described for advancing comminuted material, in whichthe compacted material .is constantly fed in a condition of uniformdensity to the point of aeration.

Check-valve mechanisms at the discharge end of the conveyor are commonlyemployed as a safeuard against blow-back. Another object of my inventionis to provide an improved check-valve mechanism which, acting inconjunction with the various other improvements will enable the con-.veyor of the present invention to operate efllciently under varyingconditions of pressure from either direction.

The further objects and advantages of my inention will becomeapparentfrom 3, consideration of the followin specification and claims taken inconnection with the accompanying drawings forming a part of thisapplication, in which:

Fig. l is an elevation, in sectin,'0i the conveying apparatus; and

Fig. 2 is an enlarged end view showing clearly 65' the construction andlocation'of the check-valve mechanism.

In the drawings, the main conveyor casing I,

having an inlet hopper I for the comminuted ma- 5 terial, is shownhoriaontally mounted on supports 1 and 8 resting on a bed-plate I.

Casing 5 has a liner Ii having a bore I! of decreasing diameter. Aconveyor screw It, of decreasing diameter comparable with the decreasein bore I2 is mounted on a hollow shaft It which extends within thecasing I. The shaft ll of conveyor screw it projects substantiallybeyondthe inlet end of the casing 5, being supported for rotation in spacedbearing blocks II restini on a pedestal It. The end of shaft Itconnects. through a suitable coupling arrangement, with a source ofmotive power, neither of which has been shown.

Between bearings II and easing I a conventional form of water-cooledjacket and dust seal is provided, encased in housing II secured to theend of easing l. The free end of the screw portion of shaft It extendsbeyond the end of casinl I, tapering inwardly. The tapered portion isprovided by a cap it attached, as by welding, to the end of the hollowshaft. The cap forms a smooth joint with the end of the hollow shaft.

Removably attached to the end of easing I is a manifold ll containingthe check-valve mechanism. Manifold It comprises a main cylindrical bodyportion 2| having flanged ends I! and II by which it may be connected tothe conveyor casing and to the conduit through which the pulverizedmaterial is to be pumped, Flange 22 extends also radially inwardly fromthe cylindrical body portion M to form a circular opening coincidingwith the narrow end of bore I 2. The inner flange portion supports thebase of a nozzle 24 having the curved form of the approach portion 4 ofa venturi and extending longitudinally within the cylindrical portion2|. Tapered plug it extends within the nozzle 24, the plug and thenozzle supplementing each other to reduce the flow area of the stream ofmaterial passing through the nozzle so as to tion. I

The check-valve II is pivotally attached to one end of a bell-crank 2trotatably mounted by means of horizontal shaft 21, the ends of-which aresupported in lugs it projecting inwardly from the walls of thecylindrical body portion II of manifold is." The other end of bell-crankII is slotted to receive a pivot pin 2|, by which it is attached to thelower end of a vertical plunger ll. Plunger II is adapted to slidedownwardly against produce a partial Venturi secthe action of acompression spring 32 in a vertical guideway drilled in a flanged boss33 formed on top of portion 2|. The upper drilled portion of the boss 33is radially recessed to receive a packing ring 34. The upper end ofplunger 3| is threaded to receive an adjustment nut 35. Compressionspring 32 acts against a washer 36 placed below adjustment nut 35 and aspring seat 37 bolted to the flange on boss 33 and forming a cover toretain the packing ring 34 in its recess. Spring 32 normally holds theplunger 3| up and the valve 25 against its seat on the mouth of nozzle24. By means of adjustment nut 35, valve 25 is made to operate undercertain predetermined conditions of pressure in the conveyor and theconduit into which it discharges. A handle so on the threaded end ofplunger 3| permits hand operation of the valve.

The pulverized material fed into hopper S is advanced by the rapidlyrotating feed-screw through the reduced portion of the casing. Thematerial is not only compacted, but its velocity is materiallyincreased. This nozzle arrangement eliminates a plug seal of denselycompacted material. In other words, instead of a physical barrier orstatic seal as a precaution against blow-back, a velocity seal isprovided. The high velocity discharge prevents blow-back under normaloperating conditions.

Gas is supplied to chamber d3 through an inlet nozzle 44 connected to asource of compressed as, not shown.

I claim:

1. In a conveyor for pulverized material in which the material isaerated to produce a condition of fluidity, a casing having an inlet formaterial to be conveyed, a rotatable-screw for advancing materialthrough said casing, a manifold on the discharge end of said casinghaving an aerating chamber with a Venturi-shaped inlet passage forreceiving material advanced by said screw, the end of said screwprojecting within the mouth of said passage and having an end tapercomplementing the curvature of said inlet passage to produce a dense,high-Velocity stream of said material discharging uniformly into saidaerating chamber, a check-valve within said chamber cooperating with thedischarge end of said inlet passage to restrict the flow of materialtherethrough, and means for aerating said material as it emerges fromsaid passage.

2. In a conveyor for pulverized material in which the material isaerated to produce a condition of fluidity, a casing having an inlet formaterial to be conveyed, a rotatable screw for advancing materialthrough said casing, said casing and said screw being tapered toincrease the density and velocity of the material being advanced, amanifold on the discharge end of said casing. havingan aerating chamberwith a Venturi-shaped inlet passage for receiving material advanced bysaid screw, the end of said screw projecting within the mouth of saidpassage and having an end taper complementin the curvature of said inletpassage to produce a dense, high-velocity stream of said materialdischarging uniformly into said aerating chamber, a check-valve withinsaid chamber cooperating with the discharge end of said inlet passage torestrict the flow of material therethrough, and means for aerating saidmaterial as it emerges from said passage.

3. In a conveyor for pulverized material in which the material isaerated to produce a condition of fluidity, a casing having an inlet formaterial to be conveyed, a rotatable screw for advancing materialthrough said casing, a manifold on the discharge and of said'casinghaving an aerating chamber with a Venturi-shaped inlet nozzle projectingtherein for receiving material advanced by said screw, the larger end ofthe nozzle passage coinciding with the discharge end of said casing, theend ofsaid screw projecting within the mouth of said passage and havingan end taper complementing the curvature of said inlet passage toproduce a dense, high-velocity stream of said material discharginguniformly into said aerating chamber, a check-valve within said chambercooperatingwith the discharge end of said inlet passage to restrict theflow of material therethrough, and means for aerating said material asit emerges from said passage;

4. In a conveyor for pulverized material, a casing having an inlet formaterial to be conveyed, a feed-screw for advancing the material throughsaid casing, a manifold on the discharge end of said casing having anaerating chamber with a Venturi-shaped inlet passagefor receivingmaterial advanced by said feed-screw, means within said inlet passageand cooperating therewith to produce a dense, high-velocity stream ofsaid material discharging uniformly into said aerating chamber, checkmeans within said chamber including a closure for the discharge end ofsaid inlet passage, said closure acting to seal the end of said inletpassage during periods of non-discharge, and means for aeratingsaidmaterial as it leaves said inlet passage.

5. In a conveyor for pulverized material, a casing having an inlet formaterial to be conveyed, a feed-screw for advancing the material throughsaid casing, a manifold on the discharge and of said casing having anaerating chamber with a Venturi-shaped inlet passage for receivingmaterial advanced by said feed-screw, means within said inlet passageforming a restricted area therein to produce a dense, high-velocitystream of said material discharging uniformly into said aeratingchamber, and check means within said chamber including a closure for thedischarge end of said inlet passage, said closure acting to seal the endof said inlet passage during periods of non-discharge.

6. In a conveyor for pulverized material wherein the material isprogressively fed into a casing and conveyed therethrough by a feedscrewwhich discharges the material at a high velocity from the casing into achamber, a nozzle attached to the dischargeend of said casing andtapered inwardly to form a Venturi-shaped passage which provides adecreasing flow area for material passing from the casing into thechamber, and a feed-screw within said casing having its forward endprojecting within said nozzle,

the forward end of said feed-screw being tapered complementary to saidnozzle, whereby a substantially uniform flow of pulverized material isprovided through said nozzle substantially free of eddies and havingsufflcient velocity to provide a seal against blow-back or said materialinto said 7. In a conveyor for pulverized material, a casing having aninlet for material to be conveyed, a feed-screw for advancing materialthrough the casing, an outlet for the material from the casing, theoutlet providing a. discharge passage of decreasing cross-section areaeffective to cause the material to issue uniformly from the outlet in adense, high-velocity stream, a 10 chamber into \vhich the material fromthe outlet is received, means for aerating the

